Neopentyl glycol (NPG), a white crystalline material having a melting point of 130° C. or more, is used as an important intermediate in a variety of synthetic resins and broadly used in industries as a raw material of various plastic coating powders, synthetic lubricating oils, plasticizers, surfactants, fiber treatment agents, etc.
Such NPG is generally prepared by preparing hydroxypivaldehyde (HPA) through aldol-condensation of isobutyraldehyde and formaldehyde and then reacting the HPA with hydrogen in the presence of a catalyst.
In the reaction, high-temperature heating should be carried out such that the HPA raw material can maintain a liquid state thereof in the section of the feed vessel to the inlet of the hydrogenation reactor. Thereby, neopentyl glycol hydroxypivalate (HPNE) as a by-product with a high boiling point, is generated before the HPA raw material is fed into the hydrogenation reactor, and thus, the content of the HPA is decreased from the inlet of the hydrogenation reactor. Finally, the content of NPG generated after hydrogenation is decreased, and the contents of by-products such as HPNE are rather increased.
Like this, the process of preparing NPG through hydrogenation of HPA has problems as follows: large amounts of by-products such as esters and iso-butanol are generated due to a high-temperature operation condition. In particular, the boiling point of an ester residue such as HPNE generated through Reaction Formula 1 below is similar to that of NPG, whereby it is very difficult to perform separation through distillation and activity of a hydrogenation catalyst is decreased.

Generation rates and amounts of the by-products are known to increase with increasing temperature due to sensitivity thereof to temperature. However, complete liquefaction of an HPA raw material becomes impossible when temperature is lowered, and thus, reactivity is decreased. On the other hand, when the HPA raw material is exposed to high temperature so as to increase reactivity, by-products are greatly increased.
At present, NPG preparation technology of converting an HPA raw material present as a solid at room temperature into a liquid state by elevating temperature to about 70° C. so as to minimize generation of by-products and then feeding the HPA raw material along with a hydrogen gas into a hydrogenation reactor is known. However, the technology still has great disadvantages such as low yield and high purification costs.